Model-independent Test of the Cosmic Distance Duality Relation

作者：Ruan, Cheng-Zong^*; Melia, Fulvio; Zhang, Tong-Jie

来源：Astrophysical Journal, 2018, 866(1): 31.

DOI：10.3847/1538-4357/aaddfd

• cosmological parameters
• cosmology: observations
• distance scale
• galaxies: active
• gravitational lensing: strong

A validation of the cosmic distance duality (CDD) relation, eta(z) = (1 + z)(2)d(A)(z)/d(L)(z) = 1, coupling the luminosity (d(L)) and angular-diameter (d(A)) distances, is crucial because its violation would require exotic new physics. We present a model-independent test of the CDD, based on strong lensing and a reconstruction of the H II galaxy Hubble diagram using Gaussian processes, to confirm the validity of the CDD at a very high level of confidence. Using parameterizations eta(z) = 1 + eta(0)z and eta(z) = 1 + eta(1)z + eta(2)z(2), our best-fit results are eta(0) = 0.0147(-0.066)(+0.056), and eta(1) = 0.10911(-0.1568)(+0.1680) and eta(2) = -0.0603(-0.0988)(+0.0999), respectively. In spite of these strong constraints, however, we also point out that the analysis of strong lensing using a simplified single isothermal sphere (SIS) model for the lens produces some irreducible scatter in the inferred CDD data. The use of an extended SIS approximation, with a power-law density structure, yields very similar results, but does not lessen the scatter due to its larger number of free parameters, which weakens the best-fit constraints. Future work with these strong lenses should therefore be based on more detailed ray-tracing calculations to determine the mass distribution more precisely.

• 出版日期2018-10-10
• 单位北京师范大学; 德州学院